1. Field of the Invention
The present invention relates to a light emitting diode (LED) lamp assembly, and more particularly to an LED lamp assembly that converts AC power to DC power.
2. Description of Related Art
Lamps can be used as either lighting or decorative devices. Tungsten light bulbs are light emitting sources for conventional lamps. With reference to FIG. 4, a conventional incandescent lamp comprises multiple tungsten light bulbs (30) and a plug (40). The tungsten light bulbs (30) are connected together in series. The plug (40) is connected to the tungsten light bulbs (30) and an external AC power source to supply power to the tungsten light bulbs (30). However, tungsten light bulbs (30) have several shortcomings, such as using a lot of electricity, generating a lot of heat, having a relatively short useful life and breaking easily.
To overcome the foregoing problems, light emitting diodes (LEDs) are becoming the newest generation light emitting sources for lamps. With reference to FIG. 5, a conventional LED lamp comprises multiple LEDs (51), a plug (60) and a current-limiting resistor (52). The LEDs (51) are connected together in series. The plug (60) is connected to the LEDs (51) and an external AC power source to supply power to the LEDs (51). The current-limiting resistor (52) is connected in series between the plug (60) and the LEDs (51) and limits current flowing through the LEDs (51).
However, the conventional LED lamp as described still has the following disadvantages.
1. The resistance of the current-limiting resistor (52) corresponds to the amount of LEDs (51) because the current-limiting resistor (52) must allow enough current to flow through the LEDs (51) so the LEDs (51) emit light. Therefore, if the amount of the LEDs (51) is changed, the resistance of the current-limiting resistor (52) has to be changed based on the number of LEDs (51).
2. The LEDs (51) only use half of the AC power supplied as operating power to emit light because the AC power includes a positive half cycle and a negative half cycle. Therefore, the conventional LED lamp wastes energy because the illumination of the light emitted by the LEDs (51) is not proportional to the output of the AC power source.
To overcome the shortcomings, the present invention provides an LED lamp assembly to mitigate or obviate the aforementioned problems.